The fast-spreading Delta variant of the coronavirus is driving up infections in developing countries that are dangerously short on Covid-19 vaccines to battle deadly surges and whose healthcare systems are struggling to cope. Indonesia, where Covid-19 cases have reached new highs, has reported about 500 deaths a day in the past week—almost triple the daily levels recorded in early June—data from its health ministry shows. Authorities are racing to add hospital beds as medical workers in parts of the country face shortages of ventilators and isolation rooms. Patients are traveling for hours for proper medical care, said the International Federation of Red Cross and Red Crescent Societies, which runs a hospital in West Java province and recently set up emergency tents on-site to accommodate the flow.

“Every day we are seeing this Delta variant driving Indonesia closer to the edge of a Covid-19 catastrophe,” Jan Gelfand, who leads the group’s delegation in the country, said recently.

As the weight of the pandemic has shifted from wealthy countries that have large supplies of vaccines to poor countries that are still struggling to secure them, the World Health Organization and developing nation governments have called for help. The U.S. and others have agreed to step up donations of excess vaccines, but those shots are still insufficient to inoculate large portions of poor country populations. Vaccines in use now in the West appear effective at protecting against the Delta variant.

In the U.K., the variant is dominant and has pushed reported daily cases up by 67% in the past week compared with the week before, but deaths are down 1.6%, government data shows. Israel, which has among the highest inoculation levels in the world, has reported small new outbreaks but just one fatality in the last two weeks of June, according to data from the World Health Organization.

Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases in the U.S., where the variant is highly prevalent, says that vaccines are effective against it. “If you look at the share of the population fully vaccinated in the United States and world-wide, they’re dramatically different, as is the dynamics of infection,” he said.

The U.S. and U.K. have fully inoculated about half their populations, but across the African continent, just over 1% of people have been fully vaccinated. Mortuaries in Zambia are full and patients are dying in hospital hallways in South Africa waiting for care.

The normally bustling streets of Bangladesh’s capital, Dhaka, have been silenced by a lockdown. WHO data shows deaths in the last week of June, numbering 716, were nearly three times higher than the first week. In India, where the Delta variant was first detected and contributed to a sharp surge in April and May, around 4% of people have been fully vaccinated. Indonesia has double-dosed around 5% of its population, according to data from the country’s health ministry.